1. Technical Field to Which Invention Belongs
The present invention relates to a hub for a wheel mounted on a wheelchair, a bicycle or the like provided with buffer means, and particularly to a hub for a wheel with buffer function in which when the vertical shock received from the road surface is received, the shock is not transmitted to the vehicle body directly but the shock is absorbed to enable running smoothly, and a wheel equipped with the hub for a wheel.
1. Related Art
At present, most of roads in our country are paved by asphalt or the like. Accordingly, no large unevenness is present on the road, and vehicles such as a wheelchair or a bicycle can be passed smoothly. Further, in order to secure the safety of passage of walkers, and vehicles such as a wheelchair, a bicycle and so on, there is provided, on the side of the automobile road, a sidewalk on which vehicles such as a wheelchair, a bicycle and so on may run. Therefore, the chance of going out by vehicles such as a wheelchair, a bicycle and so on increases. Further, it is expected that in the twenty-first century, in Japan, the society of a person of advanced age in which persons of advanced age over 65 years old occupy one person per three persons of population will come. As the life of a person extends, people disabled due to the advanced age increases rapidly. It is therefore supposed that persons of advanced age making use of a wheelchair when they go out be increased.
Further, the arrangement or adjustment of not only the outdoor roads but the living environment without difference in level are now being carried out. However, there are still present many differences in level in many road surfaces or residential facilities, and in addition, are present various differences in level in partial places such as differences in level of uneven parts appearing on the pavement of roads due to the road work or gas work, tracks caused by running of large-type vehicles and differences in level in cross-walks resulting therefrom, difference in level appearing in a boundary between a roadway and a side walk, differences in level caused by the change in passage of year of the road; and differences in level caused by a textured paving block for visual disabled persons provided on a side walk. People making use of a wheelchair such as persons of advanced age are suffered from inconvenience due to many differences in level present. For this reason, recently, there advocates the smoothness, that is, barrier-free. However, there is a problem that the vehicles such as a wheelchair or a bicycle rather have to pass carefully.
For overcoming this problem, it is necessary to further progress an improvement toward the barrier-free in the road surface or within the residence, but it requires considerable time and expenses in the improvement toward the barrier-free. In view of this, if a part of the construction of a wheelchair or the like being used now can be changed into the construction provided with a buffer mechanism, this is the best means which saves time and cost.
Incidentally, the present wheel of a vehicle such as a wheelchair or a bicycle has the construction in which spokes are stretched radially from the hub fitted in the axle and connected to the rim to apply tension to the spokes, thereby holding the rigidity of the whole wheel. Such a wheel as described above has the construction in which elasticity does not exert in a longitudinal direction vertical to the road surface. Therefore, when the vehicle such as a bicycle or a wheelchair having the wheel of construction as described passes the road or the side walk, it runs on various difference in level described above to pass. Since the shock from bottom when passing the difference in level is transmitted to a rider directly through the frame from the axle of the hub, the rider is not comfortable to ride, also influencing the durability of the vehicle body. In case the wheel mainly comprising a castor mounted as a front wheel of a wheelchair tries to ride over the difference in level, the wheel need be raised by the amount of height of the wheel, for which the rider has to use the great force. Therefore, the rider tries to move his (her) weight by force to gain momentum or makes use of reaction to ride over the difference in level. However, the shock received when riding over the difference in level is extremely great, which is not comfortable to ride for the rider.
For overcoming the disadvantages as noted above, in case of a bicycle, a spring is put into saddle or a buffer member such as a coil spring is provided on the frame itself. Further, measures are taken to lower air pressure within the tire. However, in the measures for lowering air pressure of the tire, the resistance between the wheel and the road surface is increased by lowering air pressure, further posing an inconvenience that when traveling, a burden is imposed on a rider. For overcoming these inconveniences, a proposal has been heretofore made of a wheel to which buffer means is added. For example, there is disclosed a wheel having the constitution described in Japanese Registered Utility Model Publication No. 365262.
The wheel of the prior art described above has a buffer device in which a bearing comprising a ball bearing or a roller bearing is provided in the center of a hub casing (i.e., a hub barrel), a spring receiver is provided radially on the outer circumference of the bearing, a spring receiver is provided on the inner circumference of the hub casing, and an eddy-like spring is provided between both the spring receivers described above.
The above-described prior art surely exhibits the effect relative to the vertical shock of the wheel when ridden on the difference in level, but the rigidity in a lateral direction (left and right) which is the direction of an axle due to many eddy-like springs provided radially, possibly twisting the wheel. As a result, this fails to have the function as a wheel, resulting in a decisive inconvenience of impairing the safety. This cause results from the construction in which the hub barrel forming a hub is that rotational means comprising a bearing and buffer means comprising eddy-like springs are connected together, and the eddy-like springs rotates together with the rotation of the wheel.
Further, in case of a wheelchair, as a mechanism for relieving the shock received from the difference in level, there is a buffer mechanism making use of the existing frame construction for supporting the wheel. This buffer mechanism has the construction in which for supporting a castor, a compression spring is encased in a longitudinal pipe as a frame associated and fitted in the upper part of a support shaft to receive the support shaft of the castor, whereby running over the difference in level, the support shaft of the castor is moved upward springily against the spring, and after running over the difference in level, the support shaft is moved downward again to assume the original state to enable restoring. The construction in which the support frame of the castor is provided with the buffer mechanism to absorb the shock is disclosed in the Specification of Japanese Patent Application No. Hei 8 (1996)-173482. Incidentally, the wheelchair with buffer mechanism is excellent as one to be manufactured newly. However, when the above construction is intended to be provided on the normal existing wheelchair without the buffer mechanism, large-scaled work involves, since in the normal existing wheelchair, the longitudinal pipe as a frame for supporting the castor is deposited assembled by welding as a part of the frame construction of the wheelchair body, in changing the longitudinal pipe into the longitudinal pipe provided with the above-described buffer device, thus posing a problem that time and cost are required to render unpractical.
On the other hand, there is disclosed, in Japanese Utility Model Application Laid-Open No. Hei 6 (1994)-32108, a wheelchair provided with a castor of the construction of a buffer mechanism in which one end of a downwardly biasing return spring is mounted on a wheel hub constituting a castor, the other end of the return spring is mounted on a fork supporting the castor, the return spring is interposed between the wheel hub and the fork, and the castor is moved up and down with respect to the fork by the return spring to absorb the shock. However, in case where the castor provided with the buffer mechanism is changed into the castor of the conventional wheelchair, it is necessary, since the fork for supporting the castor of the wheelchair is not the construction for mounting a return spring, to change the above-disclosed spring into a mountable fork. This work involves a problem that cannot be embodied easily.
The present invention provides a hub for a wheel having a buffer mechanism internally of a hub barrel, having an internal construction in which the great shock caused by a difference in level is relieved to enhance the comfort to ride and the durability, and the left and right lateral torsion in the direction of an axle of a wheel is eliminated to improve the safety, and further provides easily a conventional wheelchair or a bicycle as a vehicle having a buffer mechanism, by merely replacing only the wheel equipped with a hub for a wheel of high safety without changing other members.
As means of the present invention for solving the above-described problems, the invention of claim 1 provides a hub for a wheel 10 comprising a hub barrel 11, rotational means 26, buffer means 40 and a frame shaft 20 for supporting a vehicle frame 19 disposed internally of the hub barrel 11.
The invention of claim 2 provides the hub for a wheel 10 according to claim 1, wherein the hub barrel 11 has an axle 21 internally thereof, and rotational means 26 for rotatably supporting the axle 21, and buffer means 40 independently of rotation of the axle 21 are disposed within the hub barrel 11.
The invention of claim 3 provides the hub for a wheel 10 according to claim 2, wherein the buffer means 40 has the frame shaft 20 for rotatably engaging the rotational means 26 of the hub barrel 11 by a link mechanism 30 (50), and engaging and supporting a vehicle frame 19.
The invention of claim 4 provides the hub for a wheel 10 according to claim 2, wherein the rotational means 26 comprises bearings 24, 24 fitted in left and right of an axle holding member 41 (51) and the axle 21 fitted in the bearings 24, 24.
The invention of claim 5 provides the hub for a wheel 10 according to claim 1, wherein the hub barrel 11 has the rotational means 26 internally thereof, the buffer means 40 is fitted internally of the rotational means 26, and the frame shaft 20 for engaging and supporting the vehicle frame 19 is disposed on the buffer means 40.
The invention of claim 6 provides the hub for a wheel 10 according to claim 4 or 5, wherein the rotational means 26 comprises the bearings 24, the buffer means 40 comprises a link mechanism 130 engaged with the rotational means 26 independently of rotation of the rotational means 26, and the frame shaft 20 for engaging and supporting the vehicle frame 19 is an axle 121 provided on the link mechanism 130.
The invention of claim 7 provides a wheel 17 equipped with the hub for a wheel 10 according to any of claims 1 to 6.
The hub for a wheel 10 is provided, within the hub barrel 11, with the rotational means 26 of the hub barrel 11 and the buffer means 40, spokes 14, a rim 15 and a tire 16 are sequentially incorporated into the hub for a wheel 10 to assemble a wheel 17, to thereby easily obtain the wheel 17 having the buffer means 40. Further, a disk 114 can be used in place of the spoke 14 to constitutes the wheel 17, in which case the wheel 17 may be a wheel of a castor 117. Accordingly, in a vehicle 27 having no buffer means in a vehicle frame 19 or a wheel, the wheel 17 comprising a normal hub for a wheel without buffer means of the vehicle 27 is replaced by the wheel 17 equipped with the hub for a wheel 10 of the present invention to thereby enabling the provision of the vehicle 27 having the buffer means 40 very easily. A castor of a front wheel or a wheel of a rear wheel of a wheelchair having no normal buffer means is merely replaced by a castor 117 which is the wheel 17 having the buffer means 40 of the present invention or the wheel 17 of the rear wheel to provide a wheelchair 18 having the buffer means.
Particularly, since the hub for a wheel 10 according to claim 5 or 6 can be miniaturized, there can be provided a castor 117 having the buffer means 40 of the same size as the conventional castor. Accordingly, by merely exchanging with a castor shaft 119, it is possible to replace the conventional caster by the castor 117 having the buffer means 40 within the hub barrel 11. As a result, there can be provided a vehicle 27 such as a wheelchair 18 or a bicycle which can be run lightly without imposing a burden caused by rapid vibrations on a rider in the road having a difference in level.
Particularly, in the buffer means 40, since in claims 1-4, rotational means 26 of the hub barrel 11 is engaged by a cantilever link mechanism 30 or a parallel link mechanism 50, or since claim 5 or 6 comprises a link mechanism 130 engaged within rotational means 26, the torsion in the direction of the axle is prevented. Further, the buffer means 40 and the rotational means 26 are engaged by the cantilever link mechanism 30 or the parallel link mechanism 50, or by the link mechanism 130 engaged in the rotational means 26, and both of them comprise means independently of each other, that is, the buffer means 40 comprises means which is not rotated along with rotation of the hub barrel 11 but buffer-supports the axle 21 (121) movably only in the vertical direction, thus not impairing the rotation of the hub barrel 11. Accordingly, since the buffer means 40 is not rotated and can absorb only the vibration of the axle 21 in the vertical direction, there occurs no left and right lateral swaying in the axle direction of the wheel 17 or the castor 117. Accordingly, since the buffer means 40 is able to support the rotational means 26 of the hub barrel 11 in the stabilized manner, the buffer means 40 always absorbs only the rapid vibrations in the vertical direction vertical to the axle 21 (121) to suppress the vibrations, thus enabling obtaining the wheel 17 having the good comfort to ride, or the castor 117 and the wheel 17, or the vehicle 27 equipped with the castor 117 or the wheelchair 18.
As described above, the present invention exhibits the excellent effects that have not been found in prior art, that is, in the hub for a wheel according to the present invention, the buffer means is placed within the hub barrel to provide arrangements: the buffer means and the rotational means are operated independently whereby the buffer means is not rotated as the wheel rotates, and the rigidity of the wheel in the direction of the axle is enhanced; the buffer means and the rotational means are made to be independent whereby even if a trouble or a defect occurs, replacement of the respective means can be facilitated; the buffer means is provided within the hub for a wheel whereby even if the wheel runs on the difference in level directly, the shock received from the difference in level can be relieved to be comfortable to ride; the buffer means is provided within the hub for a wheel whereby the freedom of designing the vehicle is enhanced; and in the conventional vehicle without buffer means, the wheel of the vehicle is merely replaced by the wheel using the hub for a wheel according to the present invention to enable providing the vehicle having the buffer means easily.